Heretofore, the use of transparencies in military and industrial hardware has required exacting properties for their certified use. For example, a military helicopter having vast areas of transparent material will require special transparent material having identifiable indices of refraction to prevent internal reflection of sunlight. Other transparencies require resistance to penetration by projectiles. Still other transparencies are designed for resistance to abrasion.
The use of these transparencies in military and industrial applications have been severely limited by the temperatures these composite materials could withstand. Direct application of a heat source or a high energy point of origin could quickly alter the physical properties of the composite materials. Whether the thermal effects be generated by fossil fuel fires or laser application, the conventional transparencies lacked sufficient resistance to the intense heat generated. Therefore, the need exists for a material which is heat resistant, in order to complement the impact, ballistic, abrasion, or light-resistant materials presently existing in composite transparencies.
Likewise, the use of these transparencies in military and industrial application has been subjected to irreversible damage caused by the penetration of moisture into the various layers of the composite transparent structure. The susceptibility of these materials to moisture penetration in humid conditions creates a lasting haze within the transparency structure. Further, the materials must maintain adhesion among the various layers and also must maintain modulus values among the various layers at acceptable and constant levels. Therefore, the need exists for a material which is resistant to moisture permeability to protect conventional and heat-resistant transparent materials from haze characteristics but further maintains ultimate strength and constant modulus.
Although mercaptan resins, as set forth in various parent applications have fulfilled the above need, both as a composition and as an interlayer, they have some drawbacks. For example, not all mercaptan resins were soluble and suitable solvents thus requiring stronger solvents which could craze various plastic substrate surfaces. Moreover, various physical properties such as adhesion strength, elongation, modulus, and ultimate strength were only adequate.
In the parent applications, generally the following prior art patents have been cited: U.S. Pat. No. 3,134,754 to Brunner; U.S. Pat. No. 3,378,504 to Lee; U.S. Pat. No. 3,247,280 to Kanner; Japanese Pat. No. 7,243,200; German Pat. No. 1,745,149; U.S. Pat. No. 2,953,545 to Finestone; U.S. Pat. No. 3,269,853 to English; U.S. Pat. No. 3,637,591 to Coran; U.S. Patent Nos. 4,294,886 to Uram; 3,300,369 to Burkley; 3,928,708 to Fohlan et al, 3,616,839 to Burrin, 4,230,769 to Goossens; 4,081,581 to Littell; 4,343,854 to Moorman; and Japanese Pat. No. 0043,200.
However, none of these patents teach or suggest the utilization of an amino-titanate catalyst with a mercaptan resin or that good physical properties such as ultimate strength, adhesion, modulus, good moisture resistance, and the like are obtained.